There are presently several known types of fluorescent light starters which can be divided into four main groups:
1) mechanical filament heating; PA1 2) electronic filament heating; PA1 3) high voltage induction (thermal rapid-start); and PA1 4) electronic ballasts (frequency generators).
The conventional starters are found in Group 1. These contain a noble gas, at a low pressure that surrounds a pair of electrodes. One of these electrodes is formed by two bimetallic strips with different coefficients of thermal expansion. The starters are connected to the four terminals of the fluorescent light, and cause the triggering through the generation of a high voltage, the same that produces the discharge in the interior of the fluorescent tube. Although these are simple and very inexpensive, they have a number of disadvantages: their useful life is shorter than the fluorescent light's life. They are incapable of adjusting to the variation in the supply voltage. They have a slow operating cycle, of between 2 and 4 seconds which produces overheating of the tube's terminals, thus shortening the tube's useful life and producing a darkening of the ends of the tube.
Group 2 contains a variety of devices that use solid state components to replace the conventional starters. Some of them consist of an active semi-conductor device, for instance, a high-voltage transistor that acts as a switch. However, they have the annoying side effect of generating radio-frequency interference in radios and televisions near the tube. Still others use Triac thyristors as switches but they have problems triggering the fluorescent tube under low temperature conditions.
Argentine Patent No. 216,722 represents an attempt to solve the above-mentioned short-comings, by adding a capacitor to the switching element. Although this arrangement results in the triggering of the tube, due to the size of the capacitor, the triggering produces premature wear of the filaments of the fluorescent light. Consequently, the heating stage stops working, resulting in the loss of continuity.
Group 3 contains the high voltage inductive starters that are marketed as "Rapid-Start" or R.S. devices. These starters which have a special transformer and reactance coil are mounted on top of a module and pre-wired to the lighting device. They also have a capacitive strip for auxiliary external starting connected to ground.
As with all the previous devices, the "Rapid-Start" starters are connected to the four terminals of the fluorescent tube. They have the inherent disadvantage of an appreciably higher cost, and the elements that form part of such devices have a significantly larger size than other starting devices.
Group 4 contains high frequency emitter electronic ballasts without starting stages, that replace or eliminate the inductive reactance ballasts. Although these devices work satisfactorily, conventional installations need to be replaced prior to its installation. Consequently, such devices are more expensive than the other starters. Not only are they more expensive, but if they fail, their repair is relatively complicated. They also produce serious radio-frequency interference in radios and computers.
Argentine Patent 235,285 discloses an electronic starting system for fluorescent tubes. The system is based on a solid state switch that contains a thyristor which also provides a heating current to the terminals and an active capacitive branch that generates a series of high voltage pulses between the tube's electrodes. It is a disadvantage of the system, however, that it does not start with low voltage current, and that it oscillates with dimmer systems. Its functioning is also based on the continuity of the tube's filaments. As with all of the other devices describes, this starter circuit is connected to the four terminals of the fluorescent light.